Cardboard packaging sheet



FIG. 1 is a front view of a cardboard packaging sheet showing my new design; and,

FIG. 2 is a rear view thereof.

The text and shapes shown in broken lines on the surface of the cardboard packaging sheet in FIG. 1 depict environment and form no part of the claimed design. 

CLAIM The ornamental design for a cardboard packaging sheet, as shown and described. 